Brake lining testing machine



Feb. 2, 1954 H. B. BARRETT 2,667,781

BRAKE LINING TESTING MACHINE Filed Aug. 28, 1950 JNVENToR.

HARRY B. BARRETT Patented Feb. 2, 1954 UNITE anni STATE OFFICE 'l Claims.

This invention relates general to certain new and useful improvements in brake lining testing machines and, more 1iarticularly, to atesting machine for determining the degree. of adherence oetween a brake shoe and brake lining which is adhesively bonded thereto.

In recent years it has become a widely accepted practice in the automotive industry to secure brake linings 'to automotive brake slices solely by adhesives, such as thermo-setting resintype cements. Generally speaking, this type of brake shoe is referred to as a bonded shoe and the conventional rivets are either entirely climi.m nate-d or reduced to very few in number. Bonded brake linings are applied to the brake shoe under controlled. heat and pressure such that thermo-setting resin which is interposed' between the brake shoe and lining will form a tight, adherent, cementitious bond. It is, of course, obviensv that the efficiency and' safety of bonded brake shoes is dependent solely upon the effecu tiveness of the bond which' is created between the lining and the shoe, and a great deal' of difiicuity'has been experienced in achieving uniformly' satisfactory results in bonding operations.

the.

Hitherto, brake repair mechanics have relied solely upon visual inspection accompanied by manual manipulation of the bonded brake shoe and lining prior to installation the brake assembly of the automobile. If the cementitious bond looked and felt satisfactory, the shoe was l Testine by visual ininstalled on the vehicle. spection and manual manipulation is at best inexact and has been found to lead, some cases, to tragicl automobile accif ents attributable to malfunctioning of the brakes.

It is, therefore, the primary object ofthe present invention to provide a machine for testing the strength ofl the cementitious bond between a shoe and the lining bonded thereto.

it is ay further object of the r esent invention to provide a testing machine' of which is simple economical' in construction and can. beY operated quickly and efdciently by the average automotive' repair mechanic without any undue' amount of specialized training or skill.

It. isan: additional object of the present in'- vention. to provide a` testing machine of the typestated which is rugged and durable and will witlistafuiv extensive use without requiring replacement ofparts or major repairs.

It is also an object of the present invention to provide a testing machine which isA capable of rendering substantially" uniform and' standard'- ized testeresultsin asimple and readily interpretable manner.

the type stated With the above and other objects in view, my ir-iven-tionn resides in the novel features'v ofform, construction, arrangement, and combination of parts` presently described and pointed out in the claims.

In: the accompanying drawings- Figure 1 is a side elevational View partly broken away and in section ofk a brake shoe testing machine constructed in accordance with, and embodying the present invention.

Figure 2 is afront elevational View of the brake shoe testing machine.`

Figure 3 is a fragmentary rear elevational view of the brake shoe testing machine; and' Figures 4, 5 and 6 are fragmentary sectional views taken along: lines dhd, 5-5; and 6--6 respectively of Figure l.

Referring now inmore detail and by reference characters to the drawings which illustrate a preferred embodiment of the present invention, A designates a brake-:shoe testing machine comprising a hollow base casting l having integrally formed horizontally extending ears 2 which are vertically bored in the provisionof bolt-receiving apertures 3, by which the machine may be conventionally bolted down to any suitable table, pedestal, base or other support (not shown).

Formed integrally with, and projecting forwardly from, the front wall or base casting l is an outwardly extending arm i provided along its upper horizontal margin with a relatively thick top flange 5 formed in its central portion with an upwardly opening U-shapedrecess li, the lower margin of which is reinforced with a correspondingly shaped semi-circular flange l. At its forward or outer end theange 5 is integrally providedivith an. enlarged boss 8, which isrhorie sontallly bored for slidably receiving the stud Q, whichprojects outwardly therefrom at its forward' end in the provision of an impact head h. The stud ilV at its rearward end is diametrally reduced to form anv annular shoulder such diametrally reduced end projects rearwardly oven. and in upwardly spaced parallel relation to a flat. face- H milled horizontally across the top. of the flange 5- between the rear face of the boss Sandthe proximate margin of the U-shaped recess il., On. the.. opposite side ofthe Uf-shaped recess,A with. respect to the face H, the flange ii is: providedwith a vertically adjustable screw i2 i having an iifitegrallyV formed brake shoe, supporting pad i3 at its upper end andY held in any selooted" position off. vertical adjustment by a incirnut n.

Formed integrally withand extending', horizontally across the ytoprof the base casting l is a tubular housingl lli? lhaving a horizontally dis- 3 posed smooth bore I5, the axial or center line of which is coincident with the vertical center plane of the arm d. It will be noted that the axial or center line of the pin also lies in this same vertical center plane. At its rear end the housing l is diametrally enlarged in the provision of an annular diaphragm ange I6 and forwardly of the diaphragm flange for approximately half of its length the shell is counterbored in the provision of an intermediate recess Il. In addition, the shell is provided at suitably spaced points along its length with a vertically disposed vent-hole i8 and oil-hole IS. Slidably mounted in and projected forwardly from the bore l5 is a rod-shaped ram 20 provided along that portion of its length which is located in the bore |5 with a laterally presented horizontal slot 2| adapted for sliding engagement with the reduced end 22 of a stop screw 23 which is threadedly mounted in and extends through one side of the housing lll and is held in place by a lock nut 25. The reduced end 22 of the stop pin 23 will engage either of the opposite ends of the slot 2| so as to limit both forward and rearward movement of the ram 2i) and prevent unauthorized withdrawal of the ram 28 from the bore l5. At its rearward end the ram 2t projects through the recess Il and is co-axially drilled as at 25 to receive a bolt 2t which extends through a pair of diaphragm disks 2l, 28 respectively disposed on opposite sides of a flexible diaphragm 2E] which is in turn disposed around its peripheral margin against the flat face of the diaphragm flange I5, being secured in pressure tight engagement by the corresponding annular flange 3? of a cover plate 3|, the latter extending over and in outwardly spaced relation to the diaphragm 25 in the formation of a pressure chamn ber 32, the cover plate 3| being conventionally held in place by a uniformly spaced annular series of bolts 33.

It should be noted in this connection that the inner face of the cover plate 3| is provided with three horizontally inwardly projecting bosses 3Q disposed at sixty degrees from each other concentrically around the axial line of the ram 28 for endwise abutting engagement against the rearwardly presented face of the diaphragm disk 2l to act as a rear stop, against which the diaphragm-assembly will normally be biased by a heavy double-Wound compression spring 35 which is disposed encirclingly around the portion of the ram 2d which extends through the recess l1, the spring 35 being disposed abuttingly at its opposite ends respectively against the forwardly presented face of the diaphragm disk 28 and the rearwardly presented or inner end-wall of the recess l1.

The cover plate 3| is provided, vertically above its center, with an integral boss 36 which is horizontally drilled from its rear face in the provision of an air passage 3l, which communicates at its forward end with the chamber 32 and at its rearward end is counter-bored and threaded the central portion of the cover 3|, preferably, though not necessarily, in axial alignment with the ram 3B, is an air pipe i2 which is connected to a conventional source of air pressure (not shown).

The outwardly or forwardly projecting end of the ram 29 is milled off along its underface as at 43 to provide a pressure-applying portion or element 44 which is of reduced cross-sectional area and has a downwardly presented or underface d which is arcuate along a radius approximately corresponding to the radius of the brake which is to be tested. The underface 43 furthermore is spaced upwardly from the horizontal face of the brake-shoe supporting pad i3 by a distance slightly greater than the thickness of the flange f of the brake shoe S so that the pressure asserted by the ram 2s will be applied to the edge of the brake lining b. ln order to facilitate the application of pressure to brake lining IJ, the end face of the ram 253 is preferably serrated as best seen in Figure 5.

Removably mounted upon the pin 9 and resting snugly upon the upwardly presented face of the arm-flange 5 is an anvil block i6 which is likewise cut away upon its upper face to provide a shoulder Gl' and an arcuate supporting face 48, the latter being similar in contour to and in aligned registration with the supporting face I3. The vertical height of the shoulder lll is somewhat smaller than the thickness of the brake shoe flange f.

In use, the bonded brake shoe S is set down upon the supporting surfaces I3, 48 in more or less centered or balanced relationship thereon With the brake shoe web w extending freely downwardly into the U-shaped slot 6. The forwardly presented edge-face of the brake shoe will abut snugly against the shoulder 4l. Thereupon air pressure is admitted through the airl pipe d2 into the chamber 32 by means of any suitable valve (not shown). The pressure will build up to whatever maximum limit is permitted by the relief valve 38 and the diaphragm 29 will be pushed forwardly against the counterbalancing tension of the spring 35, thereby urging the ram forwardly. This initial forward movement preferably'should be slowly and carefully performed so as to bring the serrated pressure-applying element 44 gently against the edge-face of the brake vlining b directly opposite the shoulder lill. Thereupon the pressure may be allowed to build up very rapidly imposing the desired force against the brake lining b. This force or pressure may, of course, be measured by the reading of the gauge 4| and will be imposed as a shear force directly across the area in which the cementitious binder is applied. As will be seen by reference to Figure l, the shoulder 4l holds the brake shoe flange f stationary while the pressure applying element M of the ram tends to push the brake lining b forwardly, By increasing the maximum limit of pressure through'suitable manipulation of the valve element 39 it is possible to deter- `mine the maximum limit of shear force which the cementitious bond will withstand, since the ram will break the lining section b away from the brake shoe flange f at a pressure in excess of such maximum. Because some adhesives or bonding agents are brittle and will fail underV shock even though capable of withstanding gradually applied pressures, it may be desired to shock-test the bond. In such case the impact head h. of pin 9 may be tapped with a hammer maximus 5i after: the. pressi-rre tras:A beenv built: upvtof theide# limit.. It-will;..of course-g. be.understor'odg. that'` amount of' impact: can:- be. determined@ by aV process or training; in the'. use of: this* equip?- By: actual test; undo;` operating conditions' the necessary amount of strafigtlr. naquit-eds for: such cernentitiou's tends may` be: determinedi for:v any givenftype of.' loraleiv shoe;` brake: lining.: on set: of established. ineehani'calf condition:Y Thereafter; subsequentloondecl". brake shoes'. can; be: testeel to determine whether ori` n'ot the. bondwill. with@ sta-nd the@ requisite. amount oi; shea-r` force:V if, inestalilislliing'y test' results,K an:y adequate margin of safety is allowed as is'. customary in: testing all automotive equillmeni,v it` possible; to insure against improper; defectivey or unsatise factory bonding It shouldbe understoocith'at changesandmodi cations-in the'form, oonetruetion; arrangement; and combination of the several partszoi'thefbrake lining testing masi-line may:v be' made" andasubstituted for those' nerein shownv and* described without departing from: the nature and?I principle of'my'i'nvention.

Having thusY `described my invention, what I claim anddesire'to secure" byLettersfPai-,entszc l. A testing machine fordetermining the strengthV ofA seeurementbetweenf a. brake.r lining and the lor .ie shoe uponwhioii it. isamounted;

saidl testing 'machine cemprising'fa braeket'ha-.ving two upwardly presentedI spacedf slfroulders;l anvil" mounted on: one of: the sliouldei's and. being provided with an opstanding abutment., the height of? which. is slightly lessf th'afn' the thick.- ness of the brake. shoe, a support-membermount'- ed on'. the' other.v shoulderand having an. upwardly presented: face, saidy anvili andsai-el up wa-rdl'y presentediiaceof: the support-member be ing' adapted fion supporting` the brake' slooe` with oneoff itsiedge-portion-sonthe'anvil andengaeed against the abutment with the: brake lining in, upwarlolyf'presented position and with thelateral edges ofi the" brake lining free and; unsupported except foritssecurement tothe shoe and a bracket having-two upwardlypresented spaced shoulders,v an'y anvil mounted" ononefoi-.the'fshoolders and being provided with an: opstanding abutment, thel height of; whichi is slightly." less the thickness-of til-e brake shoe', a supportinembei mounted on the other shoulderrandihavan' upwardly presented-2 face, said.A anvil: and said' upwardly presented-v. face oiy the: support.- nien-Hoery being adapted for: supporting the brake shoe withv one oedge-portions: on: they anvil anni` engaged' againsttlieabutmentand,Y with the brake; lining; in upwardly presented.. position and with' the lateral edges of thelorake, lining free,

means'for applying ameasuredrforce. against and.

atriglfit anglesftotlaatlateraledgeof tlie brake lining which. is oni-the. oppositesideoi the brake shoe4 with respecty te the:v anvil-engagedportionofi the shoe whereby to.. produce relative moveent between the. shoe. and the brake lining when the force is sufficient to overcome the retentive strength of tFi-esecurement between the shoev and the lining..

2; A testing maohiue for' determiningthe strength ei"` securementl-ietween; ai Brake lining and thezbrake shoe upon which it is mounted; said' testing: machine. comprising; a brackethaving two upwardly. presented spaced shoulders;,a-n anvilmounted on one., of, the shoulders. arrrv. be-

ingl provided withV anA upstaningluabutmentthe Height" of Wlicl'r sslightly lss'than the: thcl 6' nessofth@brainssourire;a:.suppoztimemlaerrmountt @di the: anda having;y up; wardly; presented face?. saidf anvil: and'. said?y 1111- wardly presented. faee.- of. the" supportememtei; beinadaptedfon suppoi-.tingrtliebrakershoe with' one;4 ofv edge-portions; om the: anvil-1 en;- gagecti ageinstthe abutment andiwith the; brake in. upwardly." presented?. position'. and with thezlateraiifedgesfof 'the brake lningrfreeand un;-

eneept'ion its' securement' to? tlief shoe; ai. rama disposed? outwardly spacedgrelation. to one. lateral-irene off tlie'ztraitev lining; and means roi-v shitting. trier. rami against the: lateral face; of the liningfor# imposing: shearirc'e: against' and at. angles to' laterali edge: oflthebrake liningfwhichi thetoppositesi'deiof, the'ybrake slice witlii. respeot tr` the anvil'rsengagefdportion on the sliosxwherebw to producevrelative movementibetweerrtlisnoe and'.the.lorakeflining;v when force" ifsA sumcient tot overeome the. retentive strengtlii f'tlfl'ref-seeurement'betweemthe?shoeeand tlielinings..

K: testing: machine. for determining the; strength: ot? securement' between: a; lora'lrel lining and the? brake shoe". upon: whicliT it; isz mounted', saiiti testn'gz machinev comprising a: bracket; haw ing: twof upwfardly:l presentent spacedt shoulders; ,an anvil monntedlonione of th'eslrouldersandibeing provided` witnare upstamiiingV abutment. the height; off whielil ist sliglitlyf less than.V the;v thick.-v nessiof: tli'elbrakefslioe, eSupport-member mount edit-on .theotlier 'shoulderrand having an upwardly` presented face; said anvili and; said upwardly presenten fierce:4 of; triev support-mernloenA being adapted fon' Supporting the. braiseshoe withI one off its edge-portions on tire. anvil: and` engaged against tite: abutment witlr the. traire.` lining iniupwardly presented position'and withrthe lat-v eral edges.; on the brake lining: freef andi unsupported extiept: tor: itsv seourementr to the; shoe;V ay rant: disposedmoutwarniyspacewrelation: tov one laterali iaee ofi the brake lining;A springf; means fon biaising tl'iei ram.v awayf fronti the; lining. and pneumatic means?. for shifting? the ramn against tnetlateraliace offth'ei lining orimposingshearforce? against andaat right' angles` torth'at lateral edgeof the' brakefliningvwhieh is ontheopposite sidek ofthe-braker shoe.` with respect to the anvilengaefeefportion of the: s-lioevwhereby to produce relative.Y movement between; the" shoe and the bra-lie lining7 when the foreef is sufcientltoi overcon'ler the" retentive strength. off. thev securement Betweeirithe'shoeiandfthelning;

testing: maehine. for determining" the strengthoff" securement between af brakey lining and-f: the Brake? shoe?. upon: wlielrf. it' isi mount-ed; said machine comprising a base, an upwardly opening liesli'apecl bracket arm extending.' outwarmy" from they side of' the' base, said bracket incl-"udine allignt portion andi two 4upwardly presented slfi'ouRiers on oppositesidegof'tliebight; ai traire-l sii'oe supporting anvil. mounted onl tfie' sl'lonliienwhiclil isfon the outer side of5 theV Bight witfr: respectl tev the nase against which: one side of thetraire.AV shoemay abut; a bra-ke shoe-supportinglf nad? mounted'- upon the other shouloer navi-rigs. an: upwardiy presented' faceuponwliicn the; brake-ienne inayfsliiftablyrest, a horizontallir'disposed tubular hoosingmounted upon the? lippen" of the:- baser; said" tutu-lar housing Being enlareed at? one end?. thee' provi-sion off a eoncentrie': chamber; as diaphragm. mounted closureewise: screeny Seite Chambon' as cover.' plate' and secured around its periphery to the peripheral portion of the housing for holding the diaphragm tightly clamped therebetween, said cover plate being disposed for a portion of its area in outwardly spaced relation to the diaphragm in the position of a chamber across the outer face thereof, a ram shftably mounted in the housing in axial alignment with the pad and anvil and being secured at its inner end to the diaphragm for horizontal reciprocating movement responsive to the movement ofthe diaphragm, said ram projecting at its opposite end outwardly from the housing for impinging engagement against one lateral face of the brake lining, and means for introducing pressure into one of the diaphragm chambers for producing movement thereof.

5. A testing machine for determining the strength of securement between a brake lining and the brake shoe upon which it is mounted, said machine comprising a base, an upwardly opening U-shaped bracket arm extending outwardly from the side or the base, said bracket arrn including a bight portion and two upwardly presented shoulders on opposite sides of the bight, a brake shoe supporting anvil mounted on the shoulder which is on the outer side of the bight with respect to the base against which oneside of Ythe brake shoe may abut, a brake shoe supporting pad mounted upon the other shoulder and having an upwardly presented face upon which the brake shoe may shiftably rest, a horiaontallyV disposed tubular housing mounted upon the upper end of the base, said tubular housing being enlarged at one end in the provision of a concentric chamber, a `diaphragm mounted closure-wise across said chamber, a cover plate disposed across the outer face of said diaphragm and secured around its periphery to the peripheral portion of the housing for holding the diaphragm tightly clamped therebetween, said cover plate being disposed for a portion of its area in outwardly spaced relation to the diaphragm in the position of a chamber across the outer face thereof, a rain shiftably mounted in the housing in axial alignment with the pad and anvil and being secured at its inner end to the diaphragm for horizontal reciprocating movement responsive to the movement 'of the diaphragm, said ram projecting at its opposite end outwardly from the housing for impinging engagement against one lateral face of the brake lining, spring means mounted in one of said diaphragm chambers for biasing the diaphragm in the direction of the other chamber, and means for introducing pressure into said other chamber for actuating the diaphragm against the bias of said spring.

6.V A testing machine for determining the strength of securement between a brake lining and the brake shoe upon which it is mounted, said machine comprising a base, an upwardly opening U-shaped bracket arm extending outwardly from the side of the base, said bracket arm including a bight portion and two upwardly presented shoulders on opposite sides of the bight, a brake shoe supporting anvil removably mounted on one shoulder and having a laterally presented shoulder against which one side of the brake shoe may abut,'a brake shoe supporting pad adjustably mounted upon the other shoulder and having an upwardly presented face upon which the brake shoe may shiftably rest, a horizontally disposed tubular housing mounted upon the upper end ofthe base, said tubular housing being enlarged at one end in the provision of a concentric chamber, a diaphragm mounted closure-wise across said chamber, a cover plate disposed across the outer face of said diaphragm and secured around its periphery to the peripheral portion of the housing for holding the diaphragm tightly clamped therebetween, said cover plate being disposed for a portion of its area in outwardly spaced relation Yto the diaphragm in the position of a chamber across the outer face thereof, a ram shiftably mounted in the housing in axial alignment with the pad and anvil and being secured at its inner end to the diaphragm for horizontal reciprocating movement responsive to the movement of the diaphragm, said ram projecting at its opposite end outwardly from the housing for impinging engagement against one lateral face ofthe brake lining, and means for introducing pressure into one of the diaphragm chambers for producing movement thereof 7. A testing machine for determining the strength of securement between a brake lining and the brake shoe upon which it is mounted,

said machine comprising a base, an upwardly opening U-shaped bracket arm extending outwardly from the side of the base, said bracket arm including a bight portion and two upwardly presented shoulders on opposite sides of the bight, a brake shoe supporting anvil mounted against which one side of the brake shoe may abut, a brake shoe supporting pad mounted upon the other shoulder and having an upwardly presented face upon which the brake shoe may shiftably rest, a horizontally disposed tubular housing mounted upon the upper end oi the base, said tubular housing, being enlarged at one end in the provision of a concentric chamber, a diaphragm mounted closure-wise across said chamber, a cover plate disposed across the outer face of said diaphragm and secured around its periphery to the peripheral portion of the housing for holding the diaphragm tightly clamped therebetween, said cover plate being disposed for a portion of its area in outwardly spaced relation to the diaphragm in the position of a chamber across the outer face thereof, said cover plate being provided with inwardly projecting abutment means for engagement stepwise against the diaphragm, a spring operatively mounted on the opposite side of the diaphragm for holding the diaphragm against said abutment means with a predetermined amount of spring loading, a ram shiftably mounted in the housing in axial alignment with the pad and anvil and being secured at its inner end to the diaphragm for horizontal reciproeating Vmovement responsive to the movement of the diaphragm, said ram projecting at its opposite end outwardly from the housing for impinging engagement against one lateralface of the brake lining, and Vmeans for introducing pressure into one of the diaphragm chambers for producing movement thereof.

HARRY B. BARRETT.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date i 1,598,866 Lovell Sept. '7, 1926 -2,261,'783l Stull Nov. 4, 194i V2,353,056 Martindell July 4, 1944 2,425,931 Golick Aug. 19, 1947 2,498,265 Green Feb.21, 1950 

